Re: cache limit

[Erik Andersen <andersen@codepoet.org>]

On Mon Aug 18, 2003 at 11:20:24PM -0700, Andrew Morton wrote:
> Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua> wrote:
> >
> > There was a discussion (and patches) in the middle of 2.5 series
> >  about O_STREAMING open flag which mean "do not aggressively cache
> >  this file". Targeted at MP3/video playing, copying large files and such.
> > 
> >  I don't know whether it actually was merged. If it was,
> >  your program can use it.
> 
> It was not.  Instead we have fadvise.  So it would be appropriate to change
> applications such as rsync to optionally run
> 
> 	posix_fadvise(fd, 0, -1, POSIX_FADV_DONTNEED)
> 
> against file descriptors just before closing them, so all the pagecache
> gets thrown away.  (Well, most of the pagecache - dirty pages won't get
> dropped - the app must fsync the files by hand first if it wants this)

This is not supported in 2.4.x though, right?

What if I don't want to fill up the pagecache with garbage in the
first place?  When closing a file descriptor, it is already too
late -- the one time only giant pile of data has already caused
the kernel to wastefully flush useful things out of cache...

 -Erik

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Erik B. Andersen             http://codepoet-consulting.com/
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